For the last few years, I've been using a GE headset with my cell and cordless phones. It fits over the ear and the earpiece sits on the edge of the ear, not inside, which is good because the ones that sit inside rarely seem to fit me. It only costs $10 at Target and I know they are still available because I bought another one less than a week ago. Sound quality is quite decent IMO.

It has a single 2.5mm plug, and I've been looking around for an adapter to use it with a computer (for Skype, in my case) and finally found one at www.cyberguys.com for $1.99. Their part number is 190 0652. I ordered two of them yesterday, so if you want to check back with me in a few days, I'll be able to tell you how well it works.